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Setting-out Lancashire Boiler.

The Lancashire Boiler (Fig. 310) may be next considered
shortly. The back and front plates are turned, trepanned, and
drilled throughout, with the exception of the rings a, , #, and q,
these being marked afterwards from the angles. The shell plates
are prepared as before and drilled in position with axis vertical,
two by two. The angle ring a is also drilled for the shell, and
the holes at b for the flange; then all are riveted together in
batches of three, with a fixed machine, and the batches connected
by hand, or by the method at 34, Fig. 317. Next the flue plates
are rolled, welded, and flanged as at 24, Fig. 316; turned on
machine, Fig. 291; drilled in position by machine, Fig. 292 ; and
riveted together, with caulking strip between, by a portable riveter.
The plates/ and k^ are to have the angle rings/ and q attached,
but the plates themselves are first bolted to the other tubes, and
the whole tested with a long wooden lath to see if it will make up
to the same length as the boiler shell; then the end tubes turned
down accordingly. The general, straightness of the tube should
be tried during riveting, and adjusted by varying the thickness ot
the caulking strip. Now the rings of holesa, b, J>, qmay be
marked on the end plates. First the holes at /, q, and a are
marked and drilled. Then the shell is laid horizontally, the flues
blocked up in place, the back and front plates put on, and bolts
put in the rings ay /, and q ; when the holes in the shell at b may
be traced through to the flange. Removing the, ba,ck plate to
drill the flange holes, the gusset stays are prepared with their
angles riveted on, and are placed within the boiler. The back
plate is dnce more bolted on, and the whole boiler lifted on to a
trolley, which can be run under a radial drill, the latter being
preferably hinged on a wall or shop pillar so as to be at a
sufficient height while presenting no obstruction beneath. The
holes g, A, and/are cut out by drilling, and those in the shell,
for the gusset stays, lined out by squaring from the end plates,
then drilled. Entering the boiler, the workman places the stays
in position, and marks off the remaining rivet-holes in the end
plates. Removing the back plate again, the gussets are taken
away to drill, then all are replaced for riveting.

The gussets, the flange b, and the rings / and q, must be
riveted by hand/' but the ring a may be done .by machine.